Process for the preparation of 5-alkylide nenorbornene-2

ABSTRACT

A process is disclosed for the preparation of 5alkylidenenorbornene-2 for use as an important component of EPDM rubber. This product is obtained by the isomerization of 5alkenylnorbornene-2 which is accelerated by the catalytic action of certain complexes. These complexes are formed by combining organic alkalimetal compounds with alkylene diamines.

United States Patent lmai et al.

PROCESS F OR THE PREPARATION OF S-ALKYLIDE NENORBORNENE-2 Inventors: Hirosuke lmai, Yokohaini; Mitsuo' Matsuno, Kawasaki, both of Japan Assignee: Nippon Oil Tokyo, Japan Filed: Sept. 29, 1971' Appl. No.: 184,708

Company i Limited,

Foreign Application Priority Data Oct. 5, 1970 Japan ..45/86909 US. Cl. ..260/666 PY Int. Cl

Field of Search ..260/666 FY ]March 2t 1973 [56] References Cited UNITED STATES PATENTS 3,347,944 10/1967 Fritz et a]. ..260/666 PY 3,591,647 7/1971 Kochi et a1. ..260/666 PY Primary Examiner-Delbert E. Gantz Assistant ExaminerVeronica OKeefe Attorney-Buckman & Archer 57 ABSTRACT A process isdisclosed for the preparation of S-alkylidenenorbornene-2 for use as an important component of EPDM rubber. This product is obtained by the isomerizatiori of 5-alkenylnorbornene-2 which is accelerated by the catalytic action of certain con plexes. These complexes are formed by combining organic alkalimetal compounds with alkylene diamines.

8 Claims, 2 Drawing Figures swims VPATENTEUMARZOIUB W FIG.1'

0 I I I t i X(m0l/mol) FIG.2

INVENTORS HIROSUKE IMAI MITSUO MATSU NO 'nene-2 by rearranging -alkenylnorbornene-2.

Recently, a copolymer of ethylene, propylene and non-conjugated diolefins commonly known as EPDM has invited keen attention in the art for its excellent weather-proofing, ozone-resistant and heat-resistant properties. However, the EPDM polymers have the drawback that their vulcanization rate is inferior to that of widely used rubbers such as natural rubber, SBR and polybutadiene rubber. Moreover, EPDM is difficult to covulcanize with these rubbers. It has been later found that the problems of vulcanization inherent in the EPDM copolymers can be solved to a satisfactory-extent by employing, as the non-conjugated diolefin, certain S-alkylidenenorbornene-Z such as for example 5- ethylidenenorbomene-2 in the preparation of the EPDM copolymers.

Heretofore, various processes have been introduced for the preparation of 5-alkylidenenorbornene- 2, but there were no definite processes established for producing this material economically on a commercial scale at least to an extent to make the EPDM process economically feasible.

Known processes for preparing 5-alkylidenenorbornene-2 as the third component of EPDM copolymers include:

i. The Diels-Alder reaction of alkylallene with cyclopentadiene.

ii. The isomerization of l'alkylnorboradiene-2,5 produced by the Diels-Alder reaction of acetylene with alkylcyclopentadiene.

iii. The isomerization of 5-alkenylnorbornene-2 produced by the Diels-Alder reaction of diolefin with cyclopentadiene.

The processes i) and ii) are disadvantageous in that the materials, viz. alkylallene and alkylcyclopenvtadiene, are relatively expensive. The process iii) in-' volves difficulties in carrying out the isomerization such as ethylene diamine; and French Pat. 1,525,727

wherein the reaction is carried out in the presence of organic alkali metal catalysts such as a reaction product of o-chlorotoluene and sodium.

The above-exemplified prior-art isomerization processes involve a number of problems; namely, a) the catalyst activity is poor and hence, considerable amounts of catalysts are required to achieve a reasonable yield of 5-alkylidenenorbornene2, b) the isomerization rate is slow, entailing a side-production of tetrahydroindene, c) the starting materials need to be highly pure, otherwise deactivation of the catalysts is invited, and d) large quantities of expensive solvents are required. These problems have made it difficult to produce with reasonable economy the desired 5-alkylidenenorbornene-2 by rearranging 5-alkenylnorbornene-2.

Whereas, it is an object of the present invention to provide a process for the preparation of S-alkylidenenorbomene-2 which will eliminate the above-noted difficulties of the prior-art processes.

A more specific object of the invention is the provision of an improved process wherein 5-alkenyl-norbornene-2 is isomerized to 5-alkylidenenorbornene-2with use of a minimum'of catalysts, at increased reaction rate and without entailing a side-production of objectionable materials such as tetrahydroindene and polymers.

Another specific object of the invention is to provide an improved process wherein the isomerization reaction can be carried out without use of any solvent, or if desired with use of less expensive ordinary hydrocarbon solvents.

- Other features and advantages of the invention will be apparent from the detailed description given hereinafter.

The term 5-alkenylnorbornene-2 used herein represents a compound having the general formula;

where R R R and R are hydrogen, methyl or ethyl radical, ,typical examples of which are 5-vinylnorbornene-2, 5-isopropenylnorbornene-2, 5-vinyl-6-methylnorbornene-Z and the like.

The reaction of isomerizing 5-alkenylnorbornene-2 to S-alkylidenenorbomene-Z may be represented by the following formula:

The organic alkalimetal compound is represented by the general formula:

where Me is lithium, sodium or potassium, and R is an alkyl group such as methyl, ethyl, propyl, butyl, pentyl and so on, an alkenyl group such as allyl and methallyl, a cycloalkyl group such as cyclohexyl, an aryl group such as phenyl, or an arylalkyl group such as benzyl. The term organic alkalimetal compound used herein also includes a complex (charge transfer complex) of a polynuclear aromatic compound and lithium, sodium or potassium. Two or more of these mixtures may also be used. These organic alkalimetal compounds may be The amount of the complexing agent to be combined with the organic alkalimetal compound may be 0.1 to 5 mol equivalent, of the latter. Preferably this is in the range of 0.5 to 2 mol equivalent to achieve sufficient prepared within the isomerization reaction system, that 5 catalytic efficacy in the isomerization reaction accordis, in the presence of 5-alkenylnorbornene-2, or ing to the invention. Less complexing agent tends to separately without the system. suppress the formation of a complex having a rearrang- The complexing agent to be combined with the ing activity. Conversely, excessive amounts of the agent above organic alkalimetal compounds according to the are economically disadvantageous and may invite invention is an alkylene diamine derivative having decreased catalytic activity. either of the three structural formulas: The amount of the organic alkalimetal compound is not particularly critical but may be in the range of 0.1 t6 IOOHhillimbls e'raarof S-aIkenyInorbBi-nene-QI (:0 preferably 0.5 to 50 millirnols.

1)\= The isomerization of 5-a.lkenylnorbornene-2 accord- Ri R. ing to the invention may be conducted in the absence of solvents. However, it is also possible to carry out the isomerization with use of certain solvents such as for where n is an integer of two or greater numbers, and R example aliphatic or aromatic hydrocarbon which will R R and R are an alkyl, cycloalkyl or aryl group exnot deleteriously affect the reaction. Advantageously, emplified by tetra-substituted polymethylene diamines the process of the invention does not require expensive including tetramethylethylene diamine, solvents such as dimethylsulfoxide, hextetraethylethylene diamine, tetramethylpropylene me hylphosphor a de a the ike. diamine, and dimethylpiperazine. The isomerization process of the invention may be 7 carried out at temperatures between 0 and 200 C, w :preferably between and 190 C, and with or without (b) pressure. It may be continuous or by batch.

N(CHQCHQN Unreacted 5-alkenylnorbornene-2 may be separated 117 it; n v 0 by distillation from 5-alkylidenenorbomene-2 and used again for the isomerization.

The process of the invention will be further where n is two or greater integer, and R R R and R described y the following examples which are are an alkyl, cycloalkyl or aryl group exemplified by Presented y y ofiuusu'ation and not limitationsubstituted polyethylene polyamine such as pen- EXAMPLES V tamethyl diethylene trlamine.

These examples are given in respect of the rearrange- (c) ment of vinylnorbomene using different quantities of 40 tetramethylethylene diamine as combined with benzyl N-CHzCHz-N di Into a nitrogen-purged 100 milliliter stainless-steel autoclave were charged 0.2 mol 5-vinylnorbornene-2, l2 milliliters toluene solution having 2 millimol benzyl It has been found that the organic alkalimetal comsodium dissolved therein,tetramethylethylene diamine pounds when acted upon by the above exemplified in different quantities (shown in Table l) and 2.7 milcomplexing agents, tend to change prominently in liliters t-butylbenzene as the standard substance for gas color and become soluble in hydrocarbons in which the chromatography. The reaction was continued for one compounds would otherwise be insoluble. This is hour at 150 C with stirring. The reaction liquid was evidence of the formation of a complex. This complex analyzed by gas chromatography to give the following is very active as a catalyst for the isomerization of 5-aldata.

TABLE 1 Tctramethyl Unreacted Reaction product ethylene 5-vinyl n0r diamine bornene-2 ENB TH!" (millimols) (percent) (percent) (percent) Remarks Comparative Ex- 0 68. 1 23. 6 2. 4 Reaction system dark green and not homogeneous. E fir ile i 1 17. 5 80. 8 0.3 Brownish, not perfectly homogeneous solution. Example 2. l 11.7 558.2 i

i: 7 Traces Reaction system brownish, apparently homogeneous. Example 5 10 21. 7 78. 3 Traces ENB denotes 5-etl1ylidenenorb0rnene-2. "THI denotes tetrahydroindene.

kenylnorbomene-2. And as the same time, it acts to inhibit the tendency of side-production of tetrahydroindene derivatives as well as the occurrence of polymerization.

The data given in Table 1 above are further graphically illustrated by FIG. 1 of the accompanying drawing wherein the yield of S-ethylidenenorbornene-Z (ordinate Y) is plotted against the addition of tetramethylethylene diamine/benzyl sodium catalyst (abscissa X).

The data thus obtained are evidence in support of the fact that benzyl sodium and tetramethylethylene diamine, when combined, form a complex of the character which exhibits extremely high catalytic activity in the isomerization reaction of 5-vinylnorbornene-2. It has also been ascertained that the combination sodium-and-diamine catalyst acts to suppress the tendency of tetrahydroindene being by-produced in the isomerization of 5 -vinylnorbornene-2.

The benzyl sodium used in these examples was prepared by the transmetalation with toluene of phenyl sodium resulting from the reaction of chlorobenzene diamine is added to the system.

COMPARATIVE EXAMPLES II V These examples are given in respect of the isomerization of 5-vinylnorbornene-2 employing triethylamine, diethylamine, pyridine and ethylenediamine respectively as combined with benzyl sodium.

Into a nitrogen-purged stainless-steel autoclave were charged 0.2 mol 5-vinylnorbornene-2 and 2 millimol benzyl sodium prepared by the exchange reaction of phenyl sodium with 12 milliliters toluene. There were also added 2 millimols of each of the various amines. The reaction was continued for one hour at 150 C, and the resulting product was analyzed by gas chromatogl5 and sodium ra h to obtain the followin data in Table 2.

EXAMPLES VI-VII p y g These two examples are directed to the use of a com- TABLE 2 bined catalyst of phenyl sodium and Unreacted Reaction product tetramethylethylene diamine in the rearrangement 2Q reaction of vinylnorbornene.

Into a nitrogen-purged 200 milliliter four neck flask Cmpa Additive were charged 0.4 mol 5-vmylnorbornene-2 and 8 milr i i s) n r rnen -Z ENE TH! limols phenyl sodium prepared by reacting chlorobenzene with a'sodium dispersion in benzene milliliters). The reaction was continued at 50 C for 3 I none 0 68.! 23.6 2.4 9 followed by addlnol} teiraniethyl ethylepe 2 triethylamine 2 70.4 26.] 0.5 diamine. The amount of this diamine in the first m- 3 diethylamine 2 90,3 5,7 14 stance was 8 millimols (refer to point a in FIG. 2), and 4 Py 2 0 5 ethylene 2 70.1 3.0 26.5 that in the second instance was 16 milli-mols (refer to diamine point b is FIG. 2). With addition of the diamine, the react on was further continued for another three hours ENB denotes 5 ethydehenmbmene 2 at 50 C. The reaction products were analyzed by gas wT1."denotestetrahydmindenc chromatography using t-butylbenzene as the standard substance. The isomerization reaction changed with It will be noted that monofunctiona] amines such as time as graphically shown in FIG. 2, wherein the yield triethylamine, diethylamine and pyridine, and bifuncof 5-ethylidenenorbornene-2 (ordinate Y) is plotted tional amines having an active hydrogen such as ag the ti time (abscissa T). The curve VI in ethylene diamine are not capable of forming a complex the graph represents the case (Example VI) wherein 8 with benzyl sodium and hence do not contribute to the millimols tetramethylethylene diamine was added to i'somerization of 5-vinyInorbornene-2. the system while the reaction was in progress. The curve VII represents the case (Example VII) wherein EXAMPLES XI the amount Of tetramethylethylene diamine was These examples follow Example except that varilimols. As apparent from FIG. 2, the isomerization ous complexing agents are d i li f reaction is extremely slow with phenyl sodium alone, tetramethylethylene diamine as shown in Table 3- but it will increase notably when tetramethylethylene below.

TABLE 3 Unreaeted Reaction product 5vinylnorlmrnene-Q ENB* TIII Comploxing agent (percent) (percent) (purccnt) C-mnpm'ntivv Noun. 0 15X. 1 23. (3 2. 4

Example I.

IIxninplv\'lll 0:11, 1I 2 10.4 sens 'llucts NCzIIlN Example IX CH3 CH3 2 15.5 84.5 Traces NCaIIgN (In cm ExampleX CH3 /CII.; 2 0.3 93.7 Traces NC;H4N-CQII4N 0113 (711.1 out Example XI Czlll 2 17. 7 82. 3 Traces N CzIh-N Czlll S-vinylnorbomene-Z 0.2 mol Benzyl sodium 2 millimols Toluene I2 milliliters Temperature 150 C Time 1 hour The above tabulated data obtained in these examples show that benzyl sodium forms a complex with tetraethylethylene triamine and triethylene diamine, respectively. These complexes have been found highly active in the isomerization reaction according to the invention.

EXAMPLES XII XIV These examples are directed to the use of various kinds of organic alkalimetal compounds for combination with the complexing agents according to the invention.

Into a nitrogen-purged 100 milliliter stainless-steel autoclave were charged 0.2 mol 5-vinylnorbornene-2, 2 millimols tetramethylethylene diamine and 12 milliliters n-heptane having dissolved therein 2 milimols of each of the various organic alkalimetal compounds shown in Table 4.

The reaction was continued for three hours at 50 C. The gas-chromatographic data of the reaction products are given in the following Table. I

Thus, it will be noted that the complexes which result from the combination of tetramethylethylene diamine with the above various organic alkalimetal compounds are very active catalysts in the preparation of 5-ethylidene-norbornene-2 from 5-vinylnorbornene-2.

EXAMPLE XV The process of Example II was followed except that 0.25 mol 5-propenylnorbornene-2 was used instead of 5-vinylnorbornene-2. There was obtained 88.3 percent of 5-propyIidenenorbornene-2. This example indicates that the complex of benzyl sodium and tetramethylethylene diamine can be applied with excellent results also to the isomerization of 5-propenylnorbornene-2.

EXAMPLE XVI This example is given in respect of the re-arrangement of 5-vinylnorbornene-2, using normal butyl lithium as combined with dimethylpiperazine as a catalyst.

Into a nitrogen-purged milliliter stainless-steel autoclave were charged 0.2 mol S-vinylnorbornene-Z, 300 milliliters heptane solution having 2 millimols normal butyl lithium and 4 millimols dimethylpiperazine. The reaction was continued for ten hours at 50 C. The reaction product was analyzed by gas chromatography thereby revealing a yield of 68.1 percent of 5-ethylidene-norbornene-2.

What is claimed is:

1. A process for the preparation of S-aIkyIidene-norbornene-Z comprising isomerizing 5-alkenylnorbornene-2 in the presence of a catalyst consisting of an organic alkalimetal compound and a complexing agent combined therewith, said complexing agent being selected from the group consisting of a. a substituted polymethylene diamine of the formuwhere n is an integer of two or greater, and R R R and R are an alkyl, cycloalkyl or aryl radical; and (c) triethylene diamine.

2. The process as claimed in claim 1 wherein said or ganic alkalimetal compound is of the general formula:

R-Me

where R is an alkyl, alkenyl, cycloalkyl, aryl or arylalkyl radical, and Me is lithium, sodium or potassium.

3. The process as claimed in claim 1 wherein said complexing agent is used in an amount of 0.1 to 5 mols per mol of said organic alkalimetal compound.

4. The process as claimed in claim 1 wherein the isomerization reaction is carried out at temperatures raiggigl fi between 0 and 200 C.

. e process as claimed in claim 1 wherein said 5- alkenylnorbornene-2 is selected from the group consisting of 5-vinylnorbornene-2 and 5-propenylnorbornene-2.

6. The process as claimed in claim 2 wherein said organic alkalimetal compound is selected from the group consisting of benzyl sodium, allyl sodium, methyl sodium and phenyl potassium.

7. The process as claimed in claim 1 wherein said substituted polymethylene diamine is selected from the group consisting of tetramethylethylene diamine, tetraethyl-ethylene diamine, tetramethylpropylene diamine and dimethylpiperazine.

8. The process as claimed in claim 1 wherein said substituted polyethylene diamine is pentamethyl triamine. 

2. The process as claimed in claim 1 wherein said organic alkalimetal compound is of the general formula: R-Me where R is an alkyl, alkenyl, cycloalkyl, aryl or arylalkyl radical, and Me is lithium, sodium or potassium.
 3. The process aS claimed in claim 1 wherein said complexing agent is used in an amount of 0.1 to 5 mols per mol of said organic alkalimetal compound.
 4. The process as claimed in claim 1 wherein the isomerization reaction is carried out at temperatures ranging between 0* and 200* C.
 5. The process as claimed in claim 1 wherein said 5-alkenylnorbornene-2 is selected from the group consisting of 5-vinylnorbornene-2 and 5-propenylnorbornene-2.
 6. The process as claimed in claim 2 wherein said organic alkalimetal compound is selected from the group consisting of benzyl sodium, allyl sodium, methyl sodium and phenyl potassium.
 7. The process as claimed in claim 1 wherein said substituted polymethylene diamine is selected from the group consisting of tetramethylethylene diamine, tetraethyl-ethylene diamine, tetramethylpropylene diamine and dimethylpiperazine.
 8. The process as claimed in claim 1 wherein said substituted polyethylene diamine is pentamethyl triamine. 